Amendment 2 - Additional Questions an Answers.pdf
PDF 132 KB Posted
- Attached to
- Michigan River Bridge Replacement Federal contract opportunity
- Solicitation number
- 1240LT22R0056
- Issued by
- Department of Agriculture Forest Service
About this file
This document includes an amendment with additional questions and answers related to the Michigan River Bridge Replacement federal contract opportunity. The opportunity involves the removal of a temporary bridge and installation of a new single span steel beam superstructure with timber running planks and micropile foundation on National Forest System Road 792.1 over the South Fork Michigan River in Jackson County, Colorado. Acceptable bridge manufacturers are identified along with design requirements including load rating calculations and deflection limits. Clarification is provided regarding deck attachment methods and deck thickness. The US Forest Service is soliciting proposals for this project estimated between $250,000 to $500,000. Interested parties must register with the System for Award Management to be considered for award.
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Other files for this federal contract opportunity
| File | Type | Posted |
|---|---|---|
| Attachment 5 - Geotechnical Report 20211206.pdf | ||
| 1240LT22R0056_Amd 3.pdf | ||
| 1240LT22R0056_Amd2.pdf | ||
| Michigan River Questions and Answers.pdf | ||
| Site Visit Sign In Sheet.pdf | ||
| 1240LT22R0056_Amd1.pdf | ||
| Attachment 2 - Forest Service Supplemental Specs.pdf | ||
| Attachment 1 - Michigan River Plans and Drawings.pdf | ||
| 1240LT22R0056.pdf | ||
| Attachment 4 - ACROW Bridge 700XS Technical Handbook 2015 Metric.pdf | ||
| Attachment 3 - Wage Determination CO20220013.pdf |
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Text version
MICHIGAN RIVER BRIDGE REPLACEMENT
ADDITIONAL QUESTIONS & ANSWERS
AMENDMENT 2 – 1240LT22R0056
1. Could we use plans from Bridge Manufacturers than the attached plans?
Yes. Manufacturers are acceptable.
Forest Service Supplement Specification – Section 571
571.01 The fabricator must coordinate with the contractor for delivery of all materials for the bridge superstructures to the site. The bridge materials to be delivered include bearing plates, bearing pads, steel girders/diaphragms/bolts/washers/nuts/etc., galvanized steel decking, treated timber running planks, and curbs and curb supports with all associated connection hardware.
The following prefabricated modular steel bridge suppliers are AISC certified and have a history of supplying these types of bridge:
Contech Engineered Solutions Big R Manufacturing and Distributing, Inc.
P.O. Box 1290 Greeley, CO 80632-1290 800-234-0734 www.bigrbridge.com
Hamilton Construction P.O. Box 659 Springfield, OR 97477 541-746-2426 www.hamil.com
RTI Fabrication 89 Kruger Road Plains, MT 59859 406-826-5933 www.rtibridge.com
TrueNorth Steel 5405 Momont Road Momont Industrial Park Missoula, MT 59802 406-532-7103 www.truenorthsteel.com
Other manufacturers of prefabricated modular steel bridges having a minimum of five years of continuous experience in the design and construction of similar prefabricated steel bridges, and comply with Subsection 571.11, may be accepted.
Design Requirements
571.09 Design.
Design the prefabricated steel bridge girders according to AASHTO LRFD Bridge Design Specifications (AASHTO LRFD), 9th edition with current interims. A Professional Engineer registered in the state of Colorado and experienced and trained in LRFD steel design must sign and seal the design calculations and shop drawings.
Calculate loads and deflections for appropriate STRENGTH and SERVICE limit states according to Section 3 of the AASHTO LRFD Specification and the following:
a) Distribute loads according to Section 4 of the AASHTO LRFD Specifications.
b) Camber the girders according to Section 6 of the AASHTO LRFD Bridge Design Specifications for all appropriate limit states. Make girder camber 1.5 times calculated dead load deflection.
c) Limit the live load deflection to L/800. Use a dynamic load allowance of 15% in calculating live load deflections.
571.10 Design & Shop Drawing Submittal.
Within 21 days of the contract award, submit four (4) copies of the complete design and shop drawings for the Contracting Officer to review. Include plan, elevation and section views of the bridge superstructure, dimensions of all components, list of materials and specifications, weight summary, welding and connection details, and general and specific notes regarding design and construction. Allow 14 days for review time. The design and shop drawings must be approved, and any corrections made prior to beginning fabrication.
As part of the design submittal, calculate the bridge load rating in accordance with AASTHO Manual for Bridge Evaluation, 3rd edition, 2018. Rating factors must be greater than one at the inventory level for the HL-93 loading.
2. Included in the current drawings is an OLD system of attaching the wood deck……4x4 block in the valley of the 4.25” decking and bolted through the wood deck block and bottom of the bridge decking. This method is time consuming, more expensive and we have seen it to be a weaker connection, thus many years ago we moved to attach the wood deck at the crest of the decking. May we use the current deck connection (top of bridge decking) method? See attached sample drawing.
Yes. This drawing would work. For maintenance purses, we prefer the running planks could be replace from on top of the bridge.
3. Could one verify the 4.25” steel deck thickness requirement? Typical is 9Gauge. Some USFS agencies are utilizing 7Gauge.
The deck thickness is 4.25 inches. The gauge thickness is 7 Gauge. Ensure the decking could support HL-93 loading based on the girder spacing and superstructure configuration in the stamped drawings.
4. What is the deflection requirement? The USFS sometimes requires L/800.
The deflection requirement is L/800 for maximum deflection for steel structures.
5. Is a load rating required? The USFS sometimes requires this report. If so, will our inhouse method be acceptable or do we have to meet FSM 7736.23 which requires 3rd party software.
Load Rating is required. ConTech/Big R or other Bridge Manufacturers Inhouse method will be acceptable. The method for load rating would be LRFR method.
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